Study On Environmental Impact Of Bio-jet Fuel Preparation And Utilization Based On Life Cycle Assessment

With the rapid development of the aviation industry and the continuous increase of air traffic,China’s demand for jet fuel is growing rapidly.The utilization of fossil jet fuel increases the energy burden and leads to a large amount of greenhouse gas emissions in the aviation industry.It is detrimental to the sustainable development of the aviation industry and the realization of the national goal of carbon neutrality.The utilization of bio-jet fuel produced from biomass could relieve the pressure of fossil energy and reduce greenhouse gas emissions,but the technology has not been applied on a large scale in China.In this context,based on the current industrial conditions in China,the study aims to analyze the life cycle impacts of different bio-jet fuels with unified methods and system boundaries,and to provide references and suggestions for the development and commercial application of bio-jet fuel from the perspective of environmental impact.The main contents of the paper are as follows:1.In view of the characteristics of biomass resources in China and the maturity of jet fuel technology,four technical paths with potential for commercial application of aqueous phase reforming（APR）,hydrothermal liquefaction（HTL）,gasification and Fischer-Tropsch synthesis（FT）and hydrogenated esters and fatty acids（HEFA）are studied and evaluated.This paper constructs a“cradle-to-grave”system boundary based on life cycle assessment method,and deeply analyzes the technical characteristics and process models of the four technical paths.The mass yields of the four paths are 10.0%,2.5%,6.1%and 9.2%,respectively,and the calorific values of jet fuel produced are43.6,42.8,43.4 and 42.8MJ/kg,respectively.The whole life cycle data of upstream,production process and downstream stages of bio-jet fuel are sorted out,and the models are builded in Open LCA software.2.ReCiPe Midpoint and Endpoint methods are used to calculate the environmental emissions of four bio-jet fuel production paths,and the influence structures of multiple indicators are analyzed.The results show that the four pathways contribute 29.8,25.2,51.2 and 56.4 g CO₂-eq/MJ global warming potential（GWP）,respectively,which are lower than the baseline fossil fuel emissions.In addition,the minimum costs of the four paths to achieve greenhouse gas emission reduction is 2.3,1.2,3.9,and 2.9 RMB/kg CO₂-eq respectively,which are still relatively high.For human toxicity（HTP）,FT path contributes the highest 19.6 g 1,4-DCB-eq/MJ,and for photochemical oxidant formation potential（POFP）,HEFA path contributs the highest 0.61 g NMVOC/MJ.From the perspective of the overall environmental impact,the impact of bio-jet fuel on human health accounts for the largest proportion of the overall impact,HTL is the path with the lowest impact,while HEFA is the path with the greatest.From the perspective of emission structure,the influence of APR and HTL paths mainly comes from the power input in conversion stage,and that of FT path mainly comes from the oxygen consumption in the gasification process.As for the HEFA path,the biomass planting and collection stage has relatively high environmental emissions3.Considering the data quality of the input data,the uncertainty of the results is calculated.Subsequently,the sensitivity of the environmental impact of bio-jet fuel to production efficiency,electricity input and hydrogen source is evaluated.The results show that the uncertainty of GWP and POFP is small,while that of HTP is relatively large.Considering the uncertainty of GWP,the four types of bio-jet fuel could still achieve significant greenhouse gas emission reduction compared with the baseline range of fossil jet fuel.The improvement of production efficiency could effectively reduce the environmental impact,and the specific emission reduction value is closely related to the baseline value.Bio-jet fuel is also highly sensitive to the input of electricity,and the four paths could achieve the highest environmental emission reduction of 26.0%,41.9%,19.9%and 16.4%,respectively.However,according to the results,there is little difference in the improvement of environmental impact performance brought by different green power.In addition,the input of green hydrogen could reduce the GWP,POFP and overall environmental impact potential of jet fuel,but lead to the increase of HTP.The APR and HTL paths are sensitive to the application of green hydrogen,while the FT and HEFA paths are relatively insensitive.